Mission Statement and Objectives

2. Mission Statement and Objectives

4. Design Requirements Functional • Log radiation and corresponding altitude for duration of flight (up to 90,000 feet and back) • Store data on non-volatile memory • Provide power for duration of flight plus one hour set up and one hour for recovery (4 hours minimum) • Indicate the unit is powered on • Indicate system is running properly • Ensure system is both water-resistant and buoyant • Provide internal fire resistance • Provide internal temperature regulation • Ensure system will operate within temperature range and withstand forces of launch, ascent, balloon breaking, descent, and landing • Ensure system can attach to research computer payload • Ensure combined system can attach to Borealis balloon Performance • Log radiation and altitude data each second • Provide 5 watts per hour over 4 hour flight • Provide sound and/or light to indicate power is on • Provide sound and/or light to indicate the system is operating properly • Ensure water cannot leak into system and payload floats • Enable system to shut down if internal temperature exceeds 100 C • Ensure system can withstand vertical force of 10Gs and horizontal force of 5Gs (according to HASP requirements) • Ensure payload temperature stays within and will operate between -60 and 60C (external) and between -20 and 40C (internal) • Ensure pressure sensor can withstand 0-90kPa Physical • Ensure system does not exceed maximum dimensions: 5.5” by 5.5” by 5.5” • Ensure system does not exceed maximum mass: 6 lbs Reliability • Ensure system can launch twice and withstand internal tests: • Drop test • Bench-top burn test • Cold room test • Water resistance test • Pressure test • Recover all components and ensure internal components are not damaged

6. 6

7. Choosing a Prototype

8. Picking Rigid Foam Board Material *Use Polyiso bottom to comply with attaching to other payload (better drilling score)

9. Final Prototype • Structural Material • Hard Foam • Sides and Lid are polystyrene foam board • Bottom is made of polyiso foam board -Hard Foam -Gorilla Tape -Packing Tape -Fiberglass

10. Assembly • Method of Securing Electronics • ESD bag • Thinsulate bag • Packed in with shredded foam • Method of Attaching Lid • Webbing with snaps • Method of attaching to research computer payload • Bolts through our bottom into the top of the other payload • Both payloads are then placed in a Nylon bag

11. CAD Video of Assembly

12. Specifications

13. Testing

14. Accelerometer Test Results • Three axis accelerometer with a lab view program • Converted voltages to G-Force • ((V-2.7)/0.004) • Placed accelerometer inside the box (simulate what electronics feel) • Used a weight that had a mass of ~423 grams • similar dimensions to electronics • Taped accelerometer to the weight • Assembled as discussed above • Then placed the accelerometer on the outside of the box • Drop height of 3 meters

15. Accelerometer Test Results • Max Resultant G-Force • ~276 G’s • Max Resultant G-Force • ~788 G’s

16. Lid Test Results • Tied rope to bottom of box • Placed a weight inside • Used same weight as in accelerometer test • Assembled as discussed before • Swung box around in different directions • Had lid facing outward • Lid remained secure and didn’t move

17. Field Test Results • Calibrated thermocouples • Used: ice water, boiling water • Used same heater as in cold tests • Assembled in manner described above • Placed one thermocouple on the circuit board and one on the battery pack • Placed box in sun in 75⁰F weather • Measured temperature every 5 minutes • Stopped test when circuit board reached 60⁰C • Test lasted75 minutes • Corrected the temperature readings using calibration curve • Graphed data (see next slide) Thermocouple on battery pack Thermocouple on circuit board

18. Field Test Results

19. Temperature Profile Test Results • Assembled in manner described above • Placed one thermocouple on the circuit board and one on the battery pack • Placed in thermal oven • Took temperature measurements every 5 minutes • Followed the external temperature data from last years flight • Corrected the temperature readings using calibration curve • Graphed data (see next slide)

20. Temperature Profile Test Results

21. Mechanical SubsystemBill of Materials Building Materials: $119.05 packing tape, fiberglass kit, gorilla tape, gorilla glue, nylon etc. + Shredded Foam: $2.49 + Polystyrene ½” Board: $2.45 + Thinsulate: $14.99 + TI Sensor Tag: $25 Total: $163.98

23. Schematic

24. Burn In Test

25. Burn In Test Results

26. Static/ESD Bag Test Due to the packaging method, static was a concern. Using a oscilloscope the box was tested both with and without an ESD bag.

27. Conformal Coating Conformal coating was required due to both the geiger counter and the packing style of the payload. • Step 1: Cleaned boards • One bath Liquinox and DI water, followed by two alcohol baths • Step 2: Dried boards • Placed in oven for approximately 45 minutes • Step 3: Masked boards • All parts that could not be coated were masked off • Step 4: Coating boards • Boards were coated with Arathane conformal coating • Step 5: Dried boards • Boards were placed in oven for 14 hours at 50°C * A similar product was used to stake the geiger counter

28. Finished Payload

29. Budget Geiger Counter: $149.95 + Pressure Sensor: $45.44 + DC/DC Converter: $19.97 + Batteries: $69.70 + Battery Packs: $4.98 + PC Boards: $8.98 + Thermal Cutoff: $8.91 + USB Cables: $15.99 + Misc: $2.80 Total: $326.72

33. Budget Raspberry Pi: $25 + SD Card: $13 Total: $38

34. Overall Budget ME Materials $163.98 + EE Materials $326.72 + CS Materials $38.00 Total: $528.70 $71.30under budget!!!

35. Thank You!